tk canvas drag items

[Ignatz Hafflegab]

Could somebody kindly direct me to a Ruby Tk example of dragging a
tagged canvas item using canvas coordinates?

There are one or two examples supplied in Ruby 1.8.6 (Probably thanks to
Nagai-san) that allow for selecting canvas items and dragging them, but
they use the window's coordinates, and I can't figure out how to change
the code so it uses canvasx and canvasy.

Also, I'd like to know how to query a canvas widget to determine its x
or y coordinate.

Any help would be much appreciated.